At the present time, there are a variety of known techniques for compressing fibrous articles, but no known techniques provide for compressing a woven sheet article such that it can be returned to its original condition without the use of some liquid agent.
U.S. Pat. No. 2,659,935 (Hammon); U.S. Pat. No. 2,952,462 (Planin); U.S. Pat. No. 3,306,496 (Matejcek); U.S. Pat. No. 3,189,669 (Goldfein); U.S. Pat. No. 3,342,922 (Karpovich et al.); U.S. Pat. No. 3,504,064 (Bauer); and U.S. Pat. No. 4,529,569 (Palau) generally relate to methods for compressing a sponge material to a compacted, stable condition. A variety of techniques are disclosed in these patents, depending upon the application of different agents, adhesives and temperatures and pressures. However, it is noteworthy that in all these proposals, some sort of liquid agent, usually water, is required to return the sponge article to its original expanded condition. Further, in all of these patents, except for the Planin Patent, U.S. Pat. No. 2,952,462, the article has approximately the same configuration in the compressed and expanded conditions; the Planin Patent is concerned with the sponge articles, such as a toy duck, which is compressed into a different form e.g. a circular disc. Some of the patents, e.g. the Bauer U.S. Pat. No. 3,504,064 require even more extreme conditions to return the article to its original shape, e.g. the application of both heat and steam. It is also noteworthy that these patents are concerned with a sponge material, rather than woven sheet material.
There are also a number of patents relating to machines and methods of making tampons. US patents showing such methods are U.S. Pat. No. 2,134,930 (Reynolds); U.S. Pat. No. 2,336,744 (Manning); U.S. Pat. No. 2,425,004 (Rabell); and U.S. Pat. No. 2,462,178 (Ganz). These patents disclose a variety of different techniques for compressing fibrous material to form tampons. There are some notable differences from the present invention. Thus, the material used is loose fibrous material, as exemplified by the Manning Patent in which fibrous material enters through an opening and is deposited on a screen where air pressure causes it to form the pads. Further, in the nature of the product, there is no necessity for the product to be able to resume any original, un-compressed state in the absence of moisture. Further, many of these patents disclose quite elaborate folding or forming techniques, e.g. the Rabell Patent, whereas as detailed below the present invention does not require such careful folding or forming of the un-compressed article.
U.S. Pat. No. 4,096,230 is another example of a sponge material which is compressed and is capable of returning to an un-compressed condition. This again relies upon the use of moisture to return to its original shape. The article is a dehydrated prosthesis, for insertion end-wise into a body opening, e.g. the ear canal, where it absorbs moisture and returns to its original shape.
In the art of packaging woven sheet articles, a number of suppliers from the far East have developed techniques for compressing sheet articles under pressure to a compacted, solidified form, which is stable after the pressure has been released. However, this technique requires the article to be soaked in water, for its return to its original loose, un-compressed state. In general, the technique used is somewhat crude, with the applied pressure and other parameters not being significantly controlled, and indeed in many cases the operators are unaware of the exact conditions to which the articles are subjected. This technique is applied to such articles as face cloths, where clearly it is acceptable for them to be soaked in water to return the article to its original state in which it could be used. Since a face cloth is in any event wetted prior to use, this is no disadvantage.
U.S. Pat. No. 4,241,007 (Tanaka et al.) is an example of a technique for producing a compressed cloth-like article, which can be returned to its original state by absorption of water. Thus, this patent is intended for use on face cloths and the like. The patent suggests the use of very high pressures, in the range of 1,100 to 1,500 kilograms per square centimeter, preferably 1,200-1,300 kilograms per square centimeter. The larger range is equivalent to pressures in the range 15,640 to 21,330 psi, which is a very high pressure. In the light of the results discovered by the present applicant, discussed below, these pressures are surprising. In very general terms, applicant has discovered that, for a variety of materials, pressures in excess of a few thousand psi resulted in damage to the article. This U.S. Patent does refer to a published Japanese utility model Application No. 36,565/1977 which utilises a pressure as low as 30 kilograms per square centimeter, or approximately 425 psi. Again, this apparently is for an article which can be recovered to its original state by absorbing water. It is also noted that this Tanaka patented discusses in the examples the use of a binderless cellulosic non-woven fabric, which is somewhat different from the materials used by the present applicant. It is further noted that binderless cellulosic non-woven fabric appears to be higher in compression elasticity, thereby requiring higher pressures to ensure a well compressed product which is not wrinkled at the edges. Indeed, the example uses a control at a pressure 1,000 kilograms per square centimeters to show that the compression and moulding is inadequate at this pressure.
However, it will readily be appreciated that for many articles the technique of wetting a compressed article as purchased, in order to return it to an original un-compressed condition for use is entirely unacceptable. In effect, a user would have to wet the article to loosen and expand it, and then dry the article.
There are many articles for which it would be desirable to apply such a compression packaging technique. Articles such as socks, underwear, pantyhose are all relatively expensive to package. Indeed, for a product such as pantyhose, large amounts of money, time and effort are expended in developing satisfactory packaging techniques, which nonetheless require a significant amount of manual labour in the packaging of the product. Many of these articles are of relatively low cost, so that the packaging cost can be significant.